EVOH Resin Composition with High-Melting Plasticizer for Bleeding Resistance
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Solution Overview
Problem
Conventional ethylene-vinylalcohol copolymer (EVOH) resin compositions face issues with oxygen barrier properties, flexibility, and bleeding due to low melting point plasticizers, which affect the performance of molded products, especially at high humidity.
Innovation Solution
A resin composition comprising an ethylene-vinylalcohol copolymer with a hydroxyl group containing compound having a molecular weight of 200 or less, a specific hydroxyl group ratio, and a melting point within a defined range, used in a ratio of 3-15 mass% to enhance oxygen barrier properties, flexibility, and prevent bleeding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional plasticizers (propanediol, butanediol, pentanediol, propanetriol, glycerol) are used to improve flexibility and lower glass transition temperature of EVOH resin, then the resin becomes more flexible and easier to process, but the plasticizers bleed out at high temperature/high humidity due to their low melting points, resulting in impaired performance during storage
Solution Approach 1:
The invention changes the key parameter of the plasticizer from low melting point to high melting point (23°C or higher). This is achieved by selecting hydroxyl group containing compounds with specific molecular weight (200 or less) and melting point characteristics, fundamentally altering the thermal stability parameter to prevent bleeding while maintaining plasticizing effect
Solution Approach 2:
The invention applies local quality by specifying precise compositional parameters for the hydroxyl group containing compound: molecular weight of 200 or less, melting point of 23°C or higher, and hydroxyl group ratio of 0.02-0.03. These localized parameter specifications ensure the plasticizer maintains flexibility while resisting bleeding under storage conditions
2Temperature
If the molecular weight of the hydroxyl group containing compound is increased to reduce bleeding, then the plasticizing effect may be reduced and the compound may not effectively lower the glass transition temperature, but if the molecular weight is kept low to maintain plasticizing effect, the compound may bleed out more easily
Solution Approach 1:
The invention resolves this contradiction by establishing an optimal parameter range for molecular weight (200 or less) that balances plasticizing capability with bleeding resistance. This specific parameter threshold allows the compound to effectively interact with EVOH chains to lower glass transition temperature while the melting point parameter (23°C or higher) prevents bleeding
Solution Approach 2:
The invention creates a composite system by combining EVOH resin with specifically selected hydroxyl group containing compounds that have complementary properties: low molecular weight for plasticizing effect and high melting point for bleeding resistance. This composite approach achieves both flexibility and storage stability
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a resin composition with a high oxygen barrier, low glass transition temperature, and high flexibility, preventing bleeding and maintaining performance under high humidity conditions, as demonstrated by the molded products' mechanical and oxygen transmission rate characteristics.
Implementation Method 1
a hydroxyl group containing compound (B), the hydroxyl group containing compound (B) having a molecular weight of 200 or less, a ratio of the number of hydroxyl groups in one molecule relative to the molecular weight within a range of 0.02-0.03, and a melting point of 23°C or higher and 200 °C or lower
Implementation Method 2
due to their low melting points they bleed out at high temperature/high humidity (normally, at high humidity, the motility of a chain of EVOH resin increases and accordingly, the plasticizer easily moves and thus bleeds out)
Data Source
AI summary
A resin composition containing an ethylene-vinylalcohol copolymer (A) and a hydroxyl group containing compound (B), the hydroxyl group containing compound (B) having a molecular weight of 200 or less, a ratio of the number of hydroxyl groups in one molecule relative to the molecular weight within a range of 0.02-0.03, and a melting point of 23°C or higher, the content of the hydroxyl group containing compound (B) being 3-15 mass% relative to the resin composition, a molded product using the same, and a multilayer structure including a layer composed of the resin composition.